Low profile battery assembly for electrified vehicles

ABSTRACT

A battery assembly includes a plurality of battery cells and a support structure positioned about the plurality of battery cells. The support structure includes at least one sidewall and the at least one sidewall includes a first flange that extends adjacent a top surface of each of the plurality of battery cells and a second flange that extends beyond a bottom surface of each of the plurality of battery cells.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 14/538,956,which was filed on Nov. 12, 2014.

TECHNICAL FIELD

This disclosure relates to a battery assembly for an electrifiedvehicle. The battery assembly includes a battery array with at least onesidewall attached to either a tray or a cold plate along a span lengthof the assembly to maintain contact between the battery array and thecold plate for improved thermal performance.

BACKGROUND

The need to reduce automotive fuel consumption and emissions is wellknown. Therefore, vehicles are being developed that either reduce orcompletely eliminate reliance on internal combustion engines.Electrified vehicles are one type of vehicle being developed for thispurpose. In general, electrified vehicles differ from conventional motorvehicles in that they are selectively driven by one or more batterypowered electric machines. Conventional motor vehicles, by contrast,rely exclusively on the internal combustion engine to drive the vehicle.

High voltage batteries for powering electric machines of an electrifiedvehicle typically include multiple battery arrays. Each battery arrayincludes a plurality of battery cells and a support structure (i.e.,endwalls and sidewalls) that generally surrounds the battery cells tobuild the battery array. A cold plate may be positioned along a bottomof the battery cells to thermally manage the heat generated by thebattery cells.

SUMMARY

A battery assembly according to an exemplary aspect of the presentdisclosure includes, among other things, a plurality of battery cellsand a support structure positioned about the plurality of battery cells.The support structure includes at least one sidewall. The at least onesidewall includes a first flange that extends adjacent a top surface ofeach of the plurality of battery cells and a second flange that extendsbeyond a bottom surface of each of the plurality of battery cells.

In a further non-limiting embodiment of the foregoing assembly, theplurality of battery cells are positioned atop a cold plate.

In a further non-limiting embodiment of either of the foregoingassemblies, the second flange extends to a position adjacent to a sideof the cold plate and is attached to the side.

In a further non-limiting embodiment of any of the foregoing assemblies,a thermal interface material is compressed between the cold plate andthe plurality of battery cells.

In a further non-limiting embodiment of any of the foregoing assemblies,the at least one sidewall includes a first height that is greater than asecond height of the plurality of battery cells.

In a further non-limiting embodiment of any of the foregoing assemblies,the support structure includes opposing endwalls and opposing sidewalls.

In a further non-limiting embodiment of any of the foregoing assemblies,the first flange wraps around a portion of the top surface of each ofthe plurality of battery cells.

In a further non-limiting embodiment of any of the foregoing assemblies,the first flange extends in a plane that is transverse to the secondflange.

In a further non-limiting embodiment of any of the foregoing assemblies,the first flange extends in a first plane and the second flange extendsin a second plane that is parallel to the first plane.

In a further non-limiting embodiment of any of the foregoing assemblies,the second flange includes at least one opening.

In a further non-limiting embodiment of any of the foregoing assemblies,a fastener is received within the at least one opening to secure the atleast one sidewall to a cold plate.

In a further non-limiting embodiment of any of the foregoing assemblies,the assembly comprises a tray, and the at least one sidewall is attachedto the tray.

In a further non-limiting embodiment of any of the foregoing assemblies,the at least one sidewall includes a body extending between the firstflange and the second flange. The second flange includes a flaredportion that flares outwardly from the body.

In a further non-limiting embodiment of any of the foregoing assemblies,the plurality of battery cells are positioned atop a cold plate.

In a further non-limiting embodiment of any of the foregoing assemblies,the at least one sidewall is attached to one of a tray and a cold platewith a weld bead.

A battery assembly according to another exemplary aspect of the presentdisclosure includes, among other things, a tray, a cold plate positionedon the tray and a battery array including a plurality of battery cellspositioned on the cold plate. The battery array includes a sidewallattached to one of the tray and the cold plate and extending beyond abottom surface of each of the plurality of battery cells.

In a further non-limiting embodiment of the foregoing assembly, thesidewall includes a first flange that wraps around a portion of a topsurface of each of the plurality of battery cells.

In a further non-limiting embodiment of either of the foregoingassemblies, the sidewall includes a second flange that extends to aposition adjacent to a side of the cold plate.

In a further non-limiting embodiment of any of the foregoing assemblies,the sidewall is secured to one of the tray and the cold plate with atleast one fastener.

In a further non-limiting embodiment of any of the foregoing assemblies,the sidewall is secured to one of the tray and the cold plate with atleast one weld bead.

The embodiments, examples and alternatives of the preceding paragraphs,the claims, or the following description and drawings, including any oftheir various aspects or respective individual features, may be takenindependently or in any combination. Features described in connectionwith one embodiment are applicable to all embodiments, unless suchfeatures are incompatible.

The various features and advantages of this disclosure will becomeapparent to those skilled in the art from the following detaileddescription. The drawings that accompany the detailed description can bebriefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a powertrain of an electrified vehicle.

FIG. 2 illustrates a battery assembly of an electrified vehicleaccording to a first embodiment of this disclosure.

FIG. 3 illustrates an end view of a battery assembly.

FIG. 4 illustrates features associated with a sidewall of a batteryarray.

FIG. 5 illustrates a battery assembly according to a second embodimentof this disclosure.

FIG. 6 illustrates a battery assembly according to a third embodiment ofthis disclosure.

FIG. 7 illustrates a battery assembly according to another embodiment ofthis disclosure.

FIG. 8 illustrates a battery assembly according to yet anotherembodiment of this disclosure.

DETAILED DESCRIPTION

This disclosure details a battery assembly for an electrified vehicle.The battery assembly may include a plurality of battery cells and asupport structure positioned about the battery cells to build a batteryarray. The support structure includes one or more sidewalls having anextension that extends beyond a bottom surface of each of the pluralityof battery cells. The extension may be attached to either a cold plateor a tray of the battery assembly using any of a variety of fasteningtechniques. The exemplary battery assemblies of this disclosure providelow profile array to cold plate/tray attachments along a span length ofthe array to achieve proper thermal performance. These and otherfeatures are discussed in greater detail in the paragraphs that follow.

FIG. 1 schematically illustrates a powertrain 10 for an electrifiedvehicle 12. Although depicted as a hybrid electric vehicle (HEV), itshould be understood that the concepts described herein are not limitedto HEV's and could extend to other electrified vehicles, including, butnot limited to, plug-in hybrid electric vehicles (PHEV's), batteryelectric vehicles (BEV's) and fuel cell vehicles.

In one embodiment, the powertrain 10 is a power-split powertrain systemthat employs a first drive system and a second drive system. The firstdrive system includes a combination of an engine 14 and a generator 18(i.e., a first electric machine). The second drive system includes atleast a motor 22 (i.e., a second electric machine), the generator 18,and a battery 24. In this example, the second drive system is consideredan electric drive system of the powertrain 10. The first and seconddrive systems generate torque to drive one or more sets of vehicle drivewheels 28 of the electrified vehicle 12. Although a power-splitconfiguration is shown, this disclosure extends to any hybrid orelectric vehicle including full hybrids, parallel hybrids, serieshybrids, mild hybrids or micro hybrids.

The engine 14, which in one embodiment is an internal combustion engine,and the generator 18 may be connected through a power transfer unit 30,such as a planetary gear set. Of course, other types of power transferunits, including other gear sets and transmissions, may be used toconnect the engine 14 to the generator 18. In one non-limitingembodiment, the power transfer unit 30 is a planetary gear set thatincludes a ring gear 32, a sun gear 34, and a carrier assembly 36.

The generator 18 can be driven by the engine 14 through the powertransfer unit 30 to convert kinetic energy to electrical energy. Thegenerator 18 can alternatively function as a motor to convert electricalenergy into kinetic energy, thereby outputting torque to a shaft 38connected to the power transfer unit 30. Because the generator 18 isoperatively connected to the engine 14, the speed of the engine 14 canbe controlled by the generator 18.

The ring gear 32 of the power transfer unit 30 may be connected to ashaft 40, which is connected to vehicle drive wheels 28 through a secondpower transfer unit 44. The second power transfer unit 44 may include agear set having a plurality of gears 46. Other power transfer units mayalso be suitable. The gears 46 transfer torque from the engine 14 to adifferential 48 to ultimately provide traction to the vehicle drivewheels 28. The differential 48 may include a plurality of gears thatenable the transfer of torque to the vehicle drive wheels 28. In oneembodiment, the second power transfer unit 44 is mechanically coupled toan axle 50 through the differential 48 to distribute torque to thevehicle drive wheels 28.

The motor 22 can also be employed to drive the vehicle drive wheels 28by outputting torque to a shaft 52 that is also connected to the secondpower transfer unit 44. In one embodiment, the motor 22 and thegenerator 18 cooperate as part of a regenerative braking system in whichboth the motor 22 and the generator 18 can be employed as motors tooutput torque. For example, the motor 22 and the generator 18 can eachoutput electrical power to the battery 24.

The battery 24 is an example type of electrified vehicle battery. Thebattery 24 may include a high voltage traction battery pack thatincludes a plurality of battery arrays capable of outputting electricalpower to operate the motor 22 and the generator 18. Other types ofenergy storage devices and/or output devices can also be used toelectrically power the electrified vehicle 12.

In one non-limiting embodiment, the electrified vehicle 12 has two basicoperating modes. The electrified vehicle 12 may operate in an ElectricVehicle (EV) mode where the motor 22 is used (generally withoutassistance from the engine 14) for vehicle propulsion, thereby depletingthe battery 24 state of charge up to its maximum allowable dischargingrate under certain driving patterns/cycles. The EV mode is an example ofa charge depleting mode of operation for the electrified vehicle 12.During EV mode, the state of charge of the battery 24 may increase insome circumstances, for example due to a period of regenerative braking.The engine 14 is generally OFF under a default EV mode but could beoperated as necessary based on a vehicle system state or as permitted bythe operator.

The electrified vehicle 12 may additionally operate in a Hybrid (HEV)mode in which the engine 14 and the motor 22 are both used for vehiclepropulsion. The HEV mode is an example of a charge sustaining mode ofoperation for the electrified vehicle 12. During the HEV mode, theelectrified vehicle 12 may reduce the motor 22 propulsion usage in orderto maintain the state of charge of the battery 24 at a constant orapproximately constant level by increasing the engine 14 propulsionusage. The electrified vehicle 12 may be operated in other operatingmodes in addition to the EV and HEV modes within the scope of thisdisclosure.

FIG. 2 illustrates a battery assembly 54 that can be incorporated intoan electrified vehicle. For example, the battery assembly 54 could beemployed as part of the battery 24 of the electrified vehicle 12 ofFIG. 1. The battery assembly 54 includes one or more battery arrays 56for supplying electrical power to the components of an electrifiedvehicle. Although a single battery array 56 is illustrated in FIG. 2,the battery assembly 54 could include multiple battery arrays 56 withinthe scope of this disclosure. In other words, this disclosure is notlimited to the specific configuration shown in FIG. 2.

The battery array 56 includes a plurality of battery cells 58 and asupport structure 59 positioned about the plurality of battery cells 58.The battery cells 58 may be stacked side-by-side along a span length Lof the battery array 56, and may extend between opposing endwalls 60 andsidewalls 62 of the support structure 59. In one embodiment, the supportstructure 59 generally surrounds the battery array 56 on at least foursides. The sidewalls 62 of the support structure 59 may be connected tothe endwalls 60 using one or more fasteners 64 to build the batteryarray 56.

In one embodiment, the battery cells 58 are prismatic, lithium-ioncells. However, other battery cells, including but not limited tocylindrical or pouch cells, could alternatively be utilized within thescope of this disclosure.

The battery assembly 54 may additionally include a cold plate 66. Thebattery array 56 may be positioned atop a cold plate 66. The cold plate66 functions to remove heat generated by the battery cells 58 duringcertain conditions. In one embodiment, the cold plate 66 is a structuralcast cold plate. In another embodiment, the cold plate 66 is a stampedcold plate. It should be understood that the cold plate 66 may bemanufactured using any technique and using any material sufficient tocompensate for the bending moment that may develop between the sidewalls62 of the battery array 56 along the span length L. In anotherembodiment, the endwalls 60 are secured to the cold plate 66 usingadditional fasteners 64.

Referring now to FIGS. 2 and 3, one or both of the sidewalls 62 of thebattery array 56 may include a first flange 70, a second flange 72 and abody 75 that extends between the first flange 70 and the second flange72. The first flange 70 is adjacent a top surface 74 of the batterycells 58 and the second flange 72 is adjacent a bottom surface 76 of thebattery cells 58. The body 75 of the sidewalls 62 may optionally includea plurality of openings 77 (see FIG. 2) for reducing the weight of thebattery array 56.

In one embodiment, the sidewalls 62 of the support structure 59 includea first height H1 that is a greater height than a height H2 of thebattery cells 58 (best illustrated in FIG. 3). The first flange 70 maywrap around a portion of the top surfaces 74 of the battery cells 58such that it extends toward the opposite sidewall 62. The first flange70 applies a compressive force against the battery cells 58 to maintainconsistent contact between the battery cells 58 and the cold plate 66. Aseal 99 may be positioned between the first flange 70 and the topsurfaces 74 of the battery cells 58 (see FIG. 2). In another embodiment,the first flange 70 extends in a plane P that is transverse to both thebody 75 and the second flange 72 of the sidewalls 62 (see FIG. 3).

The second flange 72 extends beyond, or in this example below, thebottom surface 76 of each of the battery cells 58. The second flange 72therefore extends to position adjacent to a side 80 of the cold plate66. In one non-limiting embodiment, the second flange 72 of one or bothof the sidewalls 62 may be attached to the cold plate 66 along the spanlength L. This can be accomplished using any of a variety of fasteningtechniques. In one embodiment, the second flange 72 is welded to thecold plate 66 using one or more weld beads 82. Either a continuous weldbead 82 that extends along all or a portion of the span length L or aplurality of discrete weld beads 82 spaced along the span length L maybe employed to mount the sidewall 62 to the cold plate 66. Suitablewelding techniques include, but are not limited to, laser welding, gasmetal arc welding, spot welding, projection welding, etc. In anotherembodiment, one or more fasteners can be used to attach the sidewall 62to the cold plate 66 (see, for example, FIG. 6, discussed in greaterdetail below).

FIG. 4 illustrates additional features of a sidewall 62 of the batteryassembly 54. In one embodiment, the second flange 72 of the sidewall 62includes a flared portion 86 that is flared outwardly (i.e., in adirection away from the battery cells 58) relative to the body 75 of thesidewall 62. The flared portion 86 reduces assembly complexities of thebattery assembly 54 by simplifying placement of the battery array 56over the cold plate 66. The flared portion 86 includes enoughflexibility to allow the second flange 72 to be pushed or bent to aposition that is flush with the cold plate 66.

FIG. 5 illustrates portions of another exemplary battery assembly 154.In this disclosure, like reference numbers designate like elements whereappropriate and reference numerals with the addition of 100 or multiplesthereof designate modified elements that are understood to incorporatethe same features and benefits of the corresponding original elements.

In this embodiment, a thermal interface material (TIM) 68 may bepositioned between the cold plate 66 and the battery array 56 of thebattery assembly 154. In one embodiment, the TIM 68 is compressedbetween the cold plate 66 and the battery array 56. The TIM 68 may bemade from a material having a relatively high thermal conductivity andis configured to maintain thermal contact between the battery cells 58and the cold plate 66 in order to increase the thermal conductivitybetween these neighboring components during a heat transfer event. Forexample, the TIM 68 may distribute heat over the complete contactsurface between the battery cells (not shown) of the battery array 56and the cold plate 66. The TIM 68 may extend across an entirety of, oracross discrete portions of, the cold plate 66.

FIG. 6 illustrates another exemplary battery assembly 254. In thisembodiment, sidewalls 262 of a battery array 256 are connected to a coldplate 266 by one or more fasteners 90. The fasteners 90 may be threadedfasteners or any other type of mechanical fasteners. A second flange 272of the sidewalls 262, or the portion of the sidewalls 262 that extendsbeyond a bottom surface 276 of the battery cells 258, may include one ormore openings 92. The openings 92 align with corresponding openings 94of the cold plate 266 during assembly of the battery assembly 254. Thefasteners 90 may be received within the openings 92 and the openings 94to attach the sidewalls 262 to the cold plate 266. In one embodiment,the openings 92 and the openings 94 are dispersed along an entire spanlength L of the battery assembly 254.

FIGS. 2-6 illustrate battery assemblies that include sidewall to coldplate attachments. However, the battery array could be mechanicallyaffixed to other structures of a battery assembly. FIG. 7, for example,illustrates a battery assembly 454 that includes a battery array 456that is attached to a tray 88. In one embodiment, sidewalls 462 of thebattery array 456 are welded to the tray 88 via one or more weld beads482. A cold plate 466 may be trapped between the tray 88 and the batteryarray 456. In this embodiment, the sidewalls 462 include a first flange470 and a second flange 472 that are transverse to one another. The weldbeads 482 may be applied between the second flanges 472 and the tray 88.

FIG. 8 illustrates a battery assembly 554 that is similar to the batteryassembly 454 of FIG. 8. In this embodiment, sidewalls 562 of a batteryarray 556 include a first flange 570 and a second flange 572. The firstflange 570 extends in a first plane P1 and the second flange 572 extendsin a second plane P2 that is parallel to the first plane P1. The firstflange 570 and the second flange 572 extend in opposite directions froma body 575 of the sidewalls 562. The sidewalls 562 are attached to thetray 88 along the second flanges 572, and can be either welded ormechanically fastened using fasteners.

Although the different non-limiting embodiments are illustrated ashaving specific components or steps, the embodiments of this disclosureare not limited to those particular combinations. It is possible to usesome of the components or features from any of the non-limitingembodiments in combination with features or components from any of theother non-limiting embodiments.

It should be understood that like reference numerals identifycorresponding or similar elements throughout the several drawings. Itshould be understood that although a particular component arrangement isdisclosed and illustrated in these exemplary embodiments, otherarrangements could also benefit from the teachings of this disclosure.

The foregoing description shall be interpreted as illustrative and notin any limiting sense. A worker of ordinary skill in the art wouldunderstand that certain modifications could come within the scope ofthis disclosure. For these reasons, the following claims should bestudied to determine the true scope and content of this disclosure.

What is claimed is:
 1. A battery assembly, comprising: a cold plate; a plurality of battery cells atop said cold plate; a sidewall including a first flange adjacent a top surface of said plurality of battery cells and a second flange extending beyond a bottom surface of each of said plurality of battery cells to a position that is adjacent to a side of said cold plate, said second flange directly attached to said side; and a weld bead configured to secure said second flange to said side.
 2. The assembly as recited in claim 1, comprising a thermal interface material compressed between said cold plate and said plurality of battery cells.
 3. The assembly as recited in claim 1, wherein said sidewall includes a first height that is greater than a second height of said plurality of battery cells.
 4. The assembly as recited in claim 1, wherein said sidewall is part of a support structure of said battery assembly.
 5. The assembly as recited in claim 4, wherein said support structure includes opposing endwalls and opposing sidewalls.
 6. The assembly as recited in claim 1, wherein said first flange wraps around a portion of said top surface of each of said plurality of battery cells.
 7. The assembly as recited in claim 1, wherein said first flange extends in a plane that is transverse to said second flange.
 8. The assembly as recited in claim 1, wherein said first flange extends in a first plane and said second flange extends in a second plane that is parallel to said first plane.
 9. The assembly as recited in claim 1, comprising a tray, and said sidewall is attached to said tray.
 10. A battery assembly, comprising: a cold plate; a plurality of battery cells atop said cold plate; a sidewall including a first flange adjacent a top surface of said plurality of battery cells and a second flange extending beyond a bottom surface of each of said plurality of battery cells to a position that is adjacent to a side of said cold plate, said second flange directly attached to said side, wherein said sidewall includes a body extending between said first flange and said second flange, wherein said second flange includes a flared portion that flares outwardly from said body.
 11. A battery assembly, comprising: a tray; a cold plate positioned on said tray; a battery cell positioned on said cold plate and including a sidewall attached to one of said tray and said cold plate and extending beyond a bottom surface of said battery cell; and a weld bead configured to secure said sidewall to said tray or said cold plate.
 12. The assembly as recited in claim 11, wherein said sidewall includes a first flange that wraps around a portion of a top surface of said battery cell.
 13. The assembly as recited in claim 11, wherein said sidewall includes a second flange that extends to a position adjacent to a side of said cold plate.
 14. The assembly as recited in claim 11, wherein said sidewall is secured to said tray or said cold plate with a plurality of weld beads.
 15. The assembly as recited in claim 11, comprising a second sidewall secured to said tray or said cold plate with a second weld bead.
 16. The assembly as recited in claim 15, wherein said weld bead is located on a first side of said tray or said cold plate and said second weld bead is located on a second side of said tray or said cold plate.
 17. The assembly as recited in claim 11, wherein said sidewall includes a plurality of weight reducing openings.
 18. The assembly as recited in claim 11, wherein said weld bead is a continuous weld bead that extends along an entire span length of said cold plate. 